Antenna system



Aug. 9,1938;

w. H. WARREN ANTENNA SYSTEM Filed Feb. 21, 1935 FIG.

TL V 7/7 1211 OTHER ANTENNAS FIG. 3

2 Sheets-Sheet 1 TL ,EZLI AZ/Mnw/m INVENTOR WH. WARREN ATTOB/VEV W. H.WARREN ANTENNA SYSTEM Filed Feb. 21, 1935 2 Sheets-She et 2 FIG. 4

COUPLING DEV/CE lNl/EN TOR 'W. H. WARREN ATTORNEY Patented Aug. 9, 1938UNITED STATES PATENT ()FFICE ANTENNA SYSTEM Application February 21,1935, Serial No. 7,501 In France April 25, 1934 15 Claims. (01. 250-11)The present invention relates to improvements in antenna systems, andmore particularly in systems comprising a plurality of directionalantennas or antenna arrays.

Heretofore, in long distance broadcasting of news and in certaintranscontinental transmissions, it has been necessary to provide severaldirectional systems directed in different directions, these systemsbeing supplied simultaneously with energy modulated in the same mannerat least for high frequency. Also each directional system has beenordinarily associated with a separate radio transmitter.

One object of this invention is to transmit or receive energy in severalpredetermined directions utilizing a single aerial system.

Another object of the present invention is to .transmit, efficiently,energy in several directions with a minimum amount of apparatus.

Still another object of this invention is to radiate a maximum amount ofthe energy supplied by a transmitter to a radiating system.

According to this invention a plurality of directional arrays,preferably aperiodic, is provided, each of the arrays serving toestablish directive communications in different directions and saidarrays being fed by a common high frequency feeding system on which oneor several frequency bands may be transmitted. The several directionalarrays are associated either in series or in parallel or in combinedgrouping, with the transmission system, the arrangement being preferablysuch that a predetermined quantity of energy is radiated by each antennanetwork.

The invention will be better understood by referring tothe attacheddrawings on which like reference characters denote elements of similarfunction, and on which:

Fig. 1 represents a directional antenna of the well-known diamond orrhombic type which .is disclosed in the application of E. Bruce, SerialNo. 513,063, filed February 3, 1931;

Fig. 2 shows a series or tandem arrangement of two such rhombicantennas;

Fig. 3 shows a parallel arrangement of two rhombic antennas;

Fig. 4 shows a coupling arrangement which is suitable for transmittingtwo large bands of frequencies and for associating a rhombic antennawith a radio transmitter;

Fig. 5 shows the combination of a rhombic antenna and another antennaarranged to obtain a polarized radiation;

Fig. 6 shows an arrangement comprising a rhombic antenna and an invertedV of the type disclosed in Patent 1,899,410, E. Bruce, February 28,1933;

Fig. '7 represents a tandem arrangement of V antennas.

It is well-known that one of the properties of the rhombic antenna isits faculty of functioning efficiently for a considerable band offrequencies. This property, however, cannot be entirely utilized whenthe antenna is rendered unidirectional by means of a reflector because areflector which would be suitably placed for a "given frequency wouldnot be suitably positioned for another frequency. In order to preservethe multi-frequency characteristic of the rhombic antenna and at thesame time effect unilateral operation, the antenna is designed to havethe same characteristic impedance as the feeding system and an absorbingline is connected to the distant end of the antenna, the characteristicimpedance of the absorbing line being approximately equal to that of theantenna, whereby reflection of non-radiated energy is eliminated. Insuch an arrangement about half the total energy supplied to the feedingsystem and antenna is lost in the absorbing transmission line.

In accordance with this invention the energy feeding the absorbing lineand otherwise lost is utilized to energize a second preferably directiveantenna, this antenna being directed either in the same direction as thefirst antenna or in a dinerent direction. Alternately, this energyotherwise lost may before or after passage through a suitable rectifiersystem be employed for metering the power radiated.

Referring to the drawings the system of the prior art illustrated byFig. 1 comprises a radiating transmitter RT feeding a rhombic antenna Aby means of a transmission line TL of any suitable type, such as acoaxial line or a line comprising parallel wires. An absorbingtransmission line 'ILa, is connected to the distant end of the antennaA. Assuming that the loss in the transmission line TL is negligible, 50%of the energy supplied by the radio transmitter RT is radiated by theantenna A while the remaining 50% is dissipated in the absorbingtransmission line TLa, the loss in the terminating line TLa beingapproximately 3 decibels. Instead of dissipating 50% of the energy inthe absorbing transmission line, this energy or a part thereof is, inaccordance with this invention, employed to feed a second antenna, asillustrated by Fig. 2.

In Fig. 2, RT designates a radio transmitter, TL a transmission line ofany suitable type and A a rhombic antenna whose far end is connected bytransmission line TL to a second antenna A, at the distant end of whichisplaced an absorbing transmission line 'I'La. A coupling device CD suchas illustrated by Fig. 4 is included in the line TL. Arrows l and 2indicate respectively the desired direction of operation for antennas Aand A. In an actual case, the absorbing transmission line 11a was formedof two galvanized iron wires 480 meters long and having diameters of 2to 3 millimeters. centimeters between centers. To secure the sameattenuation with shorter lines the wires may be formed of certainsuitable alloys. 7

In the system of Fig. 2, if the losses in the transmission lines TL areignored, 50% of the power supplied by the radio transmitter RT isradiated by the transmitter A, 25% of the power is radiated by thetransmitter A, assuming that the losses in the transmission line TL-are-negligible and 25% of the energy is dissipated in the absorbingtransmission line 'I'La. It will thus clearly be seen that a portion oftheenergy otherwise dissipated maybe advantageously employed to driveanother antenna, this'antenna being'preferably provided with means forpreventing reflection' losses. V

Fig. 3 illustrates'two rhombic antennas A and A connected in parallel. Aradio transmitter RT feeds a transmission line TL of any suitable type,this line being terminated by branch lines TL and TL" which feed theantennas A and A in parallel. Antennas Aand A terminate, respectively,in absorbing transmission lines 'ILa and TLa.

The distribution of energy in the system of Fig. 3 is as follows: 25% ofthe energy supplied by radio transmitter RT is radiated by each ofantennas A and A, and 25% is absorbed by each of the lines 'I'La andTLaLI Comparing the tandem arrangement of Fig. 2 to the parallelarrangement of Fig; 3 it will be seen that in the case of a tandemconnection only a small loss is sustained since there is only onedissipating line. Other advantages of the tandem array over the parallelarray are that a simple transmission system is employed and'theimpedance in which the radio transmitter RT discharges is approximatelythe same whatever the number of antennas fed. It should be noted that inthe case of the parallel system, special precautions must be taken toproperly terminate line TL for efiicient operation over a band offrequencies. To insure this the two auxiliary transmission lines TL andTL" may be extended to the radio transmitter RT and connected inparallel at the output terminals of the power amplifying unit.

The tandem array of Fig. 2 permits the aperiodic' characteristicfaswellas the unidirectional property, of each antenna to be retained so thatone antenna may be directed in a certain direction while another isdirected in a different direction. Also a definite quantity of energymay be successively brought to the various antennas connected in tandem,a small part of this energy supplied finally arriving at the absorbingcircuit whose function is to render the system electrically long and toprevent reflection losses. By aligning groups of these antennas atvarious points increased directional propagation may be realized indiiferent directions,

Expressed on a transmission basis, thefirst antenna. is equivalentinefficiency to a single isolated rhombic antenna of the same dimensionand, in the case of a rhornbic antenna having They were spaced at.20v

sides four wave-lengths long, a gain of decibels over an ordinary dipoleis realized. The gain of the second antenna will be, in view of theenergy received by the system, 3 decibels less than that achieved by thefirst antenna, the gain being about 12 decibels over the dipole. Eachsuccessive antenna will approximately lose 3 decibels in efiiciency withrespect to the preceding antenna. In the case of four antennas connectedin tandem, the last antenna will still give about 6 decibels more than adipole. Attenuators and other devices used in high frequencytransmission circuits may be employed in the system for adjusting theamount of energy radiated by each antenna as desired. Thus, in the caseof directional antennas directed in diverse directions the quantity ofenergy radiated by each antenna may be regulated in accordance with thedistance to be covered by the various transmissions.

spirals arranged in parallel, these spirals taking up about the samespace as the primary winding.

The primary windings P1 and P2 are connected to the transmission line TLthrough coupling condensers C1 and C2. In Fig. 4 a terminal of eachprimary winding is connected to ground since one of the conductorsof thetransmission line TL is'connected to ground.

The transformers T1 and T2 transmit different frequency bands. In' aparticular installation transformer T1 was designed to transmitfrequencies included between 4,500 kilocycles per second and 12,000'kilocycles per second, and transformer T2 to transmit the frequencyband extending from 12,000 kilocycles per second to approximately 21,000kilocycles per second. The attenuation was substantially constant forfrequencies between 9,000 and 14,000 kilocycles per second. It may beadded that in constructing the antenna care must be taken to avoid anyirregularity, which would destroy the uniform character of thecharacteristic impedance. For example, the insulators should be smalland the wires should be of uniform dimensions and unassociated withconducting members such as the metal fixtures. The invention may beemployed in various arrays and systems as, for example, the systemsillustrated by Figs. 5, 6 and 7. Referring particularly to Fig. 5, thetransmission line TL" feeds through transformer T a transmission line TLwhich terminates in a transmitting antenna A of any type. Thisarrangement insures the use of energy which would otherwise be lost andwhich can be radiated by a directional or nondirectional antenna. Thephases of the currents of A and A may be adjusted to obtain ellipticallypolarized waves. 7

In Fig. 6 the antenna A is a directive V antenna array comprising aplurality of V antenna elements V1, V2, V3, V4, connected to theauxiliary transmission line TL. The V antennas V1, V2,

V3, Vi are terminated, respectively, at their far ends by suitableresistances R1, R2, R3 and R4,

point of horizontal half wave-length counter poises. Obviously, theabsorption resistances terminating the V antennas may be replaced byradiating elements. The direction of maximum propagation in a horizontalplane of the rhombic antenna and of the V antenna array coincide, asindicated by arrows 3 and 4.

Fig. 7 illustrates a tandem arrangement of two V antenna arrays. In thesystem of this figure the radio transmitter RT feeds a transmission lineTL to which are connected at points spaced a half wave-length V antennasV1, V2, V3 and Vi constituting an array. The far ends of these Vantennas are connected to another transmission line TL at points spaceda half wave-length. Transmission line TL, which may be of any length,supplies an array similar to that which has just been described andcomprising V antennas V1, V2, V3 and V4. The far ends of these Vantennas are terminated in absorbing resistances connected to ground orto counterpoises such as those illustrated by Fig. 6. Between the twogroups of antennas A and A, Fig. '7, impedance networks may be provided,such as filters, for causing the antenna A to radiate differentfrequencies from those of the antenna A. The major directive lobes ofthe antennas A and A may be similarly or differently directed.

It may be desirable to radiate different quantities of energy inspecified directions, utilizing arrays connected in tandem or parallel.In the tandem arrangement the desired division between the powerradiated in the several directions may be easily controlled withincertain limits by properly orienting the different arrays since, asalready pointed out, the successive arrays radiate gradually diminishingamounts of energy. In the parallel arrangement, the energy is dividedaccording to the law of shunted circuits and equal amounts of energy maybe radiated in the specified directions. It is clear that, in accordancewith this invention, a single radiating system may be used formulti-channel and multi-directional operation, whereby for example,communication may be realized between a single transmitter and a certainnumber of receiving stations, any one of which may be adapted to receiveone or more of the frequencies transmitted by the central radiotransmitting station.

Although the invention has been described in connection with certainspecific embodiments, it is to be understood that it is not to belimited to such embodiments. Obviously, different tandem or parallelarrangements, or combinations of such arrangements, arranged either fortransmitting or receiving, may be satisfactorily employed withoutexceeding the scope of the invention.

What is claimed is:

1. In a radio system, a transmitter, a plurality of directive antennas,said transmitter being connected directly to one antenna and onlythrough said antenna to the remaining antenna or antennas, and saidantennas being oriented for efiective operation in different directions.

2. In a radio system, a transmitter, a plurality of unilateral antennasconnected in tandem and to said transmitter, said antennas beingoriented for propagating energy in different horizontal directions.

3. In a radio system, a transmitter, a plurality of, rhombic antennasconnected in tandem, the first of which is connected to said transmitterand the last of which is terminated in its characteristic impedance.

4. In a radio system, a transmitter, a plurality of rhombic antennasarranged in tandem, the first antenna being connected to saidtransmitter and the last being terminated in its characteristicimpedance, said last antenna and the intermediateantennas each having animpedance equal to the characteristic impedance of the precedingantenna.

5. In a radio system, a transmitter, a plurality of similar rhombicantennas connected in tandem, the first of which is connected to saidtransmitter and the last of which is terminated in its characteristicimpedance, at least two of the antennas being oriented for propagationin different horizontal directions.

6. In a radio system, a transmitter, a rhombic antenna connectedthereto, each side element of said antenna being a half wave-lengthlonger than the projection of said element on the path of maximum wavepropagation, substantially, a second antenna having an impedance equalto the characteristic impedance of said first antenna, said secondantenna being connected to said first antenna.

7. A radio system, a transmitter, a rhombic antenna connected thereto,each side element of said antenna being a half wave-length longer thanthe projection of said element on the path of maximum wave propagation,substantially, a second antenna connected thereto and oriented toradiate waves polarized differently from the waves radiated by saidrhombic antenna.

8. In a radio system, a rhombic antenna connected to a V antenna, said Vantenna constituting a means for rendering the rhombic antennaunilateral.

9. In a radio system, a transmitter, an antenna array connected theretoand comprising a unidirectional antenna oriented for maximum radiationin a given direction, a second array connected to said first array andcomprising unidirectional antennas oriented for maximum radiation in asingle given direction, the frequencies of operation for said arraysbeing different.

10. In a radio system, a transmitter, a plurality of antenna arrays eachcomprising V antennas, each element of said V antennas beingapproximately a half wave-length longer than the projection of saidelement on the path of maximum propagation, said first antenna arraybeing connected to said transmitter and. second array being connected tosaid first array.

11. In a radio system, a transmitter, a plurality of antenna arrays eachcomprising V antennas, each element of said V antennas beingapproximately a half wave-length longer than the projection of saidelement on the path of maximum propagation, said arrays being connected.in tandem and each positioned for operation in a desired direction, andsaid transmitter being connected to the V antennas constituting one ofthe end arrays.

12. In a radio system, a first antenna system, a second antenna system,a translation device connected through the first system to the secondsystem, said second system constituting means for rendering the firstsystem uni-directional.

13. In a radio system, a first antenna comprising a pair of V-shapedelements having their directions of maximum radiant action superimposed,a second antenna, a translation device connected through the firstantenna to the second antenna, said second antenna having an inputimpedance equal to the characteristic impedance of the first antenna.

14. In a radio system, a first antenna arranged for operation over onefrequency band, a second antenna system arranged for operation overanother frequency band, a translation device connected through the firstsystem to the second system, said second system having an inputimpedance suitable for rendering the first system unidirectional, animpedance connected to the second system for rendering said systemunidirectional, and coupling means included between 15 said device andsaid antennas, said coupling means comprising a transformer for passingone and a transformer for passing the other of said bands with the sameattenuation.

15. In a radio system, a plurality of directive antenna systems eachoriented for operation in a desired direction and each comprising a pairof V-shaped antenna elements, each element comprising two conductors, atranslation device, said device being connected between and in serieswith the V-shaped elements of each antenna system, the conductors ofeach system having their directions of maximum radiant actionsuperimposed and aligned with the desired direction of action for thesystem.

WILLIAM H. WARREN.

